Designing Splitwise: how to approach the low-level design interview question

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Splitwise is a popular low-level design interview problem that appears simple, since everyone understands splitting a bill, but it tests object-oriented modelling. Interviewers look for how candidates structure entities, make split logic extensible across equal, exact and percentage splits, and track who owes whom. A common follow-up asks candidates to reduce a web of pairwise debts to the fewest possible settlement transfers. Answers are judged on problem solving, communication, technical execution and time management. The guide walks through clarifying requirements, identifying core classes and defending key design decisions.

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